When Tisha B’Av falls on Motzoay Shabbos, omit Tzidkos’cha Tzedek at Mincha of Shabbos. (ShA 1)
Add Havdalla into the Shemoneh Esray on Motzoay Shabbos and say Kaddish Tishkabayl after Shemoneh Esray. (Rama 1 – MB 4)
The Tisha B’Av night daavening should be slow and with crying just like mourners. So too with the reading of Eicha. (Rama 1)
At each “Eicha” raise your voice a little higher. When the chazzan reaches “Hashivaynu…”, he first allows the kahal to recite it and then the chazzan says it. Then the kahal repeats the possuk together with the chazzan. (Rama 1)
Next, the chazzan begins the kinna “Z’chor Hashem meh hoya lonu…”. After Kinnos is the Seder Kedusha beginning with “V’atta Kadosh…”. Omit “Uva L’tzion…” and “Va’ani zos…”. On Motzoay Shabbos, omit “Veehee noam…”, “Lam’natzayach binginos…” and “V’yitten l’cha…”. (ShA 2 – MB 3)
We remove the paroches from the Aron. (Rama 2)
We sit on the floor at night and in the morning of Tisha B’Av. You are allowed to put a cushion under you. If this is difficult, you can sit on a low stool. (ShA 3 – MB 11)
You should recite the Eicha and Kinnos even if you are alone. (MB 5)
Sit in the dark at night, except for the minimum light that you need for reading. And even in the morning, do not light a lamp for the chosson. Light candles only for a Bris Mila. (ShA 3 – MB 14, 15)
Since Tisha B’Av is called a “moed” we omit Tachanun, Tziduk Hadin, Selichos, Kayl Erech Apayim and Lam’natzayach. However, crying and eulogies are appropriate. (ShA 4 – MB 17, 42)
Begin Shacharis a little earlier than usual, unless it causes the Kinnos to end much before chatzos. The Kinnos should end a little before chatzos, then go visit the cemetary. By then it will be chatzos and you may sit on regular chairs. (ShA 3 – MB 12, 16)
During Kinnos, do not talk or go outside – it will distract your mind from the mourning. (ShA 5)
Throwing things to one another in shul is a big avaira – it shows light mindedness in the shul. (MB 22)
The custom is to express a little comfort after Kinnos are over. (Rama 5)
An ovel within three days may go to shul for the morning kinnos only. After three days, he can go even at night. (ShA 6 – MB 24)
An onen stays home at night. In the morning, after the burial he may stop into shul until the end of Kinnos – then go and stay home. (MB 24)
When a Bris Mila falls on Tisha B’Av, it is held right after Kinnos. If the mother is present she should drink the wine, otherwise you can give the wine to a child that is of the age of chinuch for berachos. The one that drinks it should hear the Hagoffen and not talk until she tastes the wine. (ShA 7 – ShaH 26)
Four people may change to Shabbos clothes only for the duration of the Bris: the father, the mother, the mohel and the sandek. After the Bris they change back. If the clothes are brand new, they aren’t allowed to be worn. (ShA 8 – MB 32, 33, 34)
Shoes may not be worn for the Bris. (BeH “umuttar.”)
Those four must complete their fast unless the fast is a “nidche” from Shabbos. In such a case they should fast until after daavening Mincha Gedola, bathe, hold the Bris and drink the wine. They can now eat but they should not hold the big feast until nightfall. (ShA 9 – MB 35, 36, 37 – ShaH 37)
A chosson on the day of his chuppa has the same din mentioned just above. Even when the other days of his Seven Days of Feasting fall on a “nidche”, there is basis for breaking the fast. (MB 35 – ShaH 34)
A person who is somewhat ill, and a pregnant women who suffers discomfort are exempt from fasting on a “nidche”. (BeH “v’aino”)
Those who will be eating on a “nidche” must make Havdalla on a cup of wine beforehand. (MB 37)
A Pidyon Haben that falls (the 31st day) on a “nidche” is grounds for breaking the fast after Mincha. It is a Yom Tov for the father and the cohen. Nevertheless, the seuda should not be held until after the fast is over. (MB 38)
After chatzos, you are allowed to prepare a meal to break the fast. (MB 39)